Contbol system fob fuel burners



Dec. 27, 1927.

J. H. STEWART CONTROL SYSTEM FOR FUEL BURNERS Filed April 20. 1926 I NVEN TOR. 731471, 522541)?- By Qmum/ A TTORNE Y.

Patented Dec. 27, 1927.

UNITED STATES JOHN H. STEWART, OF CINCINNATI. OHIO.

CONTROL SYSTEM FOR FUEL BURNERS.

Application filed April 20, 1928.

My invention relates to fuel burner control systems which incorporate inautomatic controlling devices the operation of a fuel burner ignitionsystem, the power element with which the burner is operated, and themeans of supplying the burner with fuel.

It is my object to provide an electric eircuit in a control system whichwill effect automatic operation of the burner and which also willprovide exceptional safety to the system against excessive How of oil incase of nonignition, and which will prevent wasteful use of electriccurrent in case the storage tank is exhausted of oil. It is also myobject to provide a circuit which will break the circuit of the powerline upon failure of the automatic controlling devices to functionproperly.

It is the object of my invention to provide electrical controlling meansparticularly for an oil burning system which is composed of a burneroperated by an electric motor, an igniter with which the fuel is ignitedand a pump with which fuel is supplied to a gravity flow reservoir.

Incorporated in my control system in cone bination with an air currentsupply means for a fuel burner such as is described in my co-pendingapplication, Serial No. 93,- 008, filed the 8th of March, 1926, it is myobject to provide a novel quick acting thermostat, actuated by the heatof the burner, which will automatically inhibit the ignition means afterthe fuel is ignited and coincidentally prohibit the opening of a masteror time limit switch, thus maintaining the burner in operativecondition.

Further incorporated in my controlling system is a novel master or timeswitch, the object of which is the inhibition of the electric powerafter a certain interval. It is my object to utilize the time switch forthe primary control of the entire system and to so connect the timeswitch element which controls the system that upon failure of the burnerto light properly the entire system is inhibited, but with thesuccessful lighting of the burner the system becomes automaticallyregulating, being controlled by the usual room thermostat or theauxiliary boiler control in case the system is for a hot water, or steamheating plant.

It is my object to provide a control system which will operateautomatically without the necessity for a pilot light, so that when noheat is required there is no waste of fuel.

Serial No. 103,350.

The above and other objects which will be noted in the ensuingdescription, are incorporatcd in a controlling system which I haveillustrated in its preferred embodiment.

Referring to the drawings:

Figure I. is a diagrammatic elevation of the system including thepreferred wiring arrangement.

l igure 2 is a horizontal section of the ther mostatic ignition controlbox.

Generally indicated in the diagrammatical elevation in Figure 1. I haveshown the fuel burner 1 preferably disposed on the shaft of a motor 2.An igniter 3 is shown, the preferred type illustrated being a carbon arelighter as described in my co-pending application Serial No. 94,080,filed March 11th. 1920. Current which is supplied from the power feedlines el passes first through the main control box assembly indicated at5 and then through the thermostatically controlled ignition control box6. The pump 7 which provides a supply of fuel for the burner ispreferably of the type described in my co-pendin application Serial" No.97,106, filed Harch 9A, 1926, comprising a gravity reservoir with whichoil is supplied to the burner and an automatically controlled pump whichkeeps the reservoir filled as long as a supply is required for theburner and then shuts off when the supply is no longer required.

Incorporated in the main control box 5 I have shown a preferred type oftime switch indicated at S which cuts off the current to the entiresystem if the burner fails to light within a certain time. The powerfeed line indicated at the left in Figure 1 will be traced first. It isrn'eforably connected with a room thermostat 9 and a boiler controlelement 10 in accordance with usual boiler room and furnace installationpractice. The room thermostat and boiler control. however. are optionaland depend on the requirements of the heating system. From the contactpost 11 in the main control box, if the thermostat and boiler controlare in- ((uporaled in the system a line 12 connects with the one of theterminals 13 of the room thermostat. the line 11: passing to thethermostat and returning to the other terminal 15 from which the line 10connects with one of the terminals 17 of the line 18 which leads to theboiler control element. The return from the boiler control element maybe suitably connected to a terminal 19 from which (ill Lima

sure. As noted these controls torni no part of my invention and thestructure oi the several controlling elements may he any desired type.

To the terminal 19, one line indicated at is conne to the input ctedwhich leads end 8 of a time switch. The preferred struc ture ot the trueSWltll is as indicated with a spring EU'ET n'ioi'uted on a bracket 95clectri will connected \.ith the input line 90. The spri arm is l l 1 iiiizectcd position by a bimetallic e iich is mounted on bracket 2? woichis electucally connected with the output line 28 u leads to the system,resistance e 29 is mounted in proximity to the lit) forming a sericonnection, l3 ,stwee put lines of the swit interval the resistance (3metallic element so that it floating element and releas which springstoward. t1 7 in dotted lines and hrcalis "he circuit at the positionindicated at I also provide a hand operated plunger 31 which sets thetime ritch hack to connected position. From the output end of th timeswitch the line 28 leads to a tern' connection 32. FY0121 the terinina aline leads connection to one oi the terminals 2-3:) from which a line nt \LLu endir; p so that race of its ioin (accepting that my icl'udcs thecontrol with which fuel is oi operai oin i supplied to the hurt iprovided for ano her con =ol 0L the fuel suopl r bi incorpora ed in inpump assembly, o in cluding the pump in my systenn l have pro vided adouble means of positively inhihijnp; a supply of fuel to the learnerwhich is an added insurance against flooding the boiler or furnace roomfloor with fuel and creating an additional fire hazard.

lhe line 22 from the terminal 58 leads to the righthand terminal in thethermostaLic ignition control box 6. This hos: is en closed in a casing39 ha *ing an air supply pipe which during the operation of the burneris supplied with air from the on source as the burner. The end il whichis mounted in close to the tiurnace lire ix :1 so that a spiral 4hmounted on a shaft -13 the coiling; and uncoiling oi the elei'uent 4-2till: a mercury tube set which is carried by the shaft 4:3 in aclockwise or coun er clockwise directioa depending on whether thefurnace is heating up or cooling oil". in order to protect the tube i lfrom tilting too far in either direction, nus indicated at are providedwhich pin 60 at the limit of counter and c tube by the 1, ilecliion ishunt with the resisti it switch and i turiace ligi then iIl L'GLl in 1.T I. bimetallic element stahl' ed which is in c oi: the

' l s the time switci from tripping; and hrealrirg the circuit Foincreasing the apidity with which the tlierniosta'ic control operates anair cond iit all) is disposed in ie casi g 39 which directs a current ofair against a flapper Valve d5, thus cut '11 oil 1 7 2:7 hii-netalhc theflow of incuccd air to the spiral element so that there will he aquicker rise in temoerature from the oil i'lZZHlQ due to the ahseuce theinduced air. Also when the burner motor stops, the flap-- per valveopens liy rrai'ity anowinu; induced air to reach he spiral hi netzrllicole nent :1 2 and cause a quicker reduction in temperature after the oilllamc has ,uone out.

The conuectionav with the motor 2 are through a line eiG which extendsfrom the right hand terminal. 52 lo the terminal 4:? fr nu which. theline l8 0 ends to the iijictor and through the line l9 from the motor toa terminal :30 which connected to a grouml 31. l have iturthei provideda line 52 ere tenoiug from the termii'ial which is councclied with aline 553 wl'iich. Lads hack to the main control; he 4'') in which it isconnected with a terminal list which has a line connecting; it with theterinii 1.;

The motor connecting lines c lines which lead to a cut-off value a herahly of the solenoid type which inhibits the flow of oil to the burnerunless the motor is operating. From the terminal 32- in the main controlbox a line 57 is connected with the centrally disposed terminal 38 whichsup plies the current for the ignition with the mercury tube tilted in acounter clockwise position.-

The operation of the system is as follows: Starting the system with thetime switch unset theon'lg necessary manic adjustment iui) is thepushing in of the spring arm 24: to locked position with the end of thebimctaL lic element 26. Then the current is supplied both to the pump 7and through the line 57 to the central terminal in the box 6. As themercury tube will be tilted to the left current will pass through theline H to the carbon lighter. Under normal conditions the line e6 willalso provide current for operating the motor 2 and the burner will.ignite. As soon as the burner is lighted the mercury tube is tilted tothe right, which shuts off the igniter. Should the ignitor light and thefuel fail to light the time switch will, after the required inter 'al,break the entire circuit so that everything will be shut off. It thenbecomes necessary for the operator to examine the system to discoverwhat is wrong and before the system can be started up the plunger 3Lmustagain be pushed in to set the time switch. If during the operationof the motor. due to some such cause as insuflicient draft, the tire issmothered and goes out the mercury tube will be titled to the left. Thiswill allow the continued operation of the burner with th lighter onuntil the burner is again lighted or until the time switch again cutsoff the entire system.

illodifications in structure will readily occur to those skilled in theart, but in so far as these changes amount to no more than thesubstitution of well known equivalents for those devices which I employwhich are well known in the art I consider such changes within the scopeof my invention.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. In combination with an electrical control system for an automaticfuel burner, a thermostatic switch comprising a housing, a bimetallicelement, a shaft, a mercury tube and aflapper valve mounted within thehousing adapted to close off the flow of induced air over the bimetallicelement during periods of burner operation, and adapted to open bygravity, thus admitting induced air to the bimetallic element when theburner fails to properly ignite.

2. In combination with a fuel burning system, and an electrical systemfor controlling the operation thereof, a thermostatic element adapted tocontrol the operation of said electrical system, and means actuable byair currents for accentuating the operation of said thermostaticelement, said means comprising an air conduit with an open end directedtoward said thermostatic element, and a member adapted to inhibit thepassage of air through said conduit during periods of fuel burningoperation.

3. In combination with a fuel burning system. and an electrical systemfor controlling the operation thereof, a thermo static element adaptedto control the operation of said electrical system, and means ofaccentuating the operation of said thermostatic element. said meanscomprising an air conduit with an open end directed toward saidthcriuos-tatic element, and a member adapted to inhibit the passage ofair through said conduit during periods of fuel burning operation. saidmember being so supported with relation to said air conduit as to dropby gravity out of inhibiting position during periods of cessation offuel burning operation.

In combination with a fuel burning system, and an electrical system forcontrolling the operation thereof, a thermostatic element against whichcooling air currents may be directed, adapted to control the operationof said electrical system, and means actuable by air currents forcontrolling the flow of cooling air currents against said thermostaticelement.

In combination with a mercury switch for controlling an automatic fuelburning system, a spiral bimetallic element against which cooling aircurrents may be directed, having a fixed end, a shaft extending axiallyoi the spirial element and connected with its movable end, and saidmercury switch mounted on said shaft, and air pressure controlled meansfor controlling the flow of cooling air currents against the bimetallicelement.

JOHN H. STE'WART.

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